Sun Microsystems SPARCstation 20, Service Manual

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Chapter 11 System Board and Component Replacement 159
DSIMMs, VSIMMs, and NVSIMMs
The SPARCstation 20 system supports as many as eight dynamic single in-line
memory modules (DSIMMs). DSIMMs are available in three capacities;
16-Mbyte, 32-Mbyte, and 64-Mbyte. In addition, the SPARCstation 20 system
supports up to two video single in-line memory modules (VSIMMs) and one non-
volatile SIMM (NVSIMM). VSIMMs are available in two capacities:
4-Mbyte and 8-Mbyte.
Each SIMM card has horizontally mounted intergrated circuits (ICs) on both sides of
the card. The part of the card that plugs into the memory slot has a scalloped edge
with a conductive surface, that is known as gold fingers.
Removing and installing all capacities and types of SIMMs (DSIMM, VSIMM,
NVSIMM) is identical. The following sections provide a brief discussion of DSIMMs,
VSIMMs, and NVSIMMs and is followed by procedures for removing and installing
a SIMM.
Caution –
A SIMM is made of delicate electronic components that are extremely
sensitive to static electricity. Handle a SIMM only by the edges. Ordinary amounts of
static from clothes or work environment can damage a SIMM. Do not touch the
components on a SIMM or any metal parts. Wear a grounding strap before
unpacking a SIMM and while handling a SIMM.
DSIMM
FIGURE 11-20
and
FIGURE 11-21
show front and back views, respectively, of a DSIMM.
When installed, the key notch should be near the DSIMM ejector levers.
FIGURE 11-20
DSIMM, Front View
Key notch